"The incident took place around 8 am. Around six persons were injured and admitted to hospitals. More pile ups at the same stretch were reported later in which some other persons suffered injuries," he said.

An eyewitness at the spot claimed that one person was apparently killed in the mishap. However, police denied that any death had taken place.

The eyewitnesses also claimed that 20 vehicles were involved in the pile-up.

Yamuna Expressway management said they have put up display boards for drivers to drive slow and use fog lights during bad weather.

As there were no buildings around the 165 kilometre stretch, the fog was dense.

"We appeal to the drivers to drive carefully on the Yamuna Expressway and Noida-Greater Noida expressway," said the SP.